Cartridge fuse



y 931. c. T. MCDONALD ET AL ,3

CARTRIDGE FUSE Original Filed Nov. 5, 1927 l 4* "31 36 Wm 6W fjlwwmfi 4 M znmaw Patented May 12,

neirransrAres PATENT oFFIcE CLARENCE T. MCDONALD AND HERBERT RAY COOK, OF CHICAGO, ILLINOIS, ASSIGNORS TO JEFFERSON ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS CARTRIDGE FUSE Application filed November 8, 1827, Serial No. 230,707. Renewed September 24, 1930.

This invention relates to cartridge fuses of the so-called knife blade type and more particularly to a renewable fuse of this type in which the terminal blades are incorporated in a unitary structure which is bodily removable from the casing, and has for its general object the provision of a fuse of new and improved construction and which is particularly adapted to facilitate and expedite the replacement of the fusible element.

Another object of the invention is to'provide a fuse with novel'means for closing the ends of the casing and for securing the terminal blades thereto.

Another object is to provide a novel fuse structure in which the end closure securing devices are permanently mounted on the casing.

Another object is to provide a cartridge fuse in which the terminal blades are incorporated in a unitary structure of new and improved CODStI'LlCtlOIL.

A. further object is to provide simple and novel means for securing the terminal blades of a fuse rigidly together in spaced relation.

Further objects and advantages will be come apparent from the following detailed description in connection with the accompanying drawings, in which Figure 1 is a longitudinal view partly in central section of one form of the invention.

Fig. 2 is a similar view taken in a plane at right angles to that ofFig. 1.

Figs. 3 and 4 are elevational and plan views respectively of the terminal unit.

Fig. 5 is a section taken in the plane of the line 55 of Fig. 2..

Fig. 6 is a section taken in the plane of the line 66 of Fig. 3. r Fig. 7 is a perspective view of one end of the terminal unit showing a. connecting clip of the unit.

lVhile We have shown in the drawings and will herein describe in detail the preferred embodiment of our invention, it will be understood that this disclosure is given for the purpose of representing a specific way of carrying out the invention and is not intended as a limitation thereof to the construction dis- DO closed. Vv e aim to cover in the appended claims all modifications and alternative constructions falling within the scope of the invention as limited by the state of the prior art.

In attaining the objects of the invention a renewable cartridge fuse is provided comprising generally a casing of insulating material havinga metallic bushing secured at each end and a terminal blade unit adapted to pass through said casing and to be rigidly secured to said bushings by means of end closures non-rotatably associated with said terminal blade unit at each end thereof, and members freely rotatable on but non-removable from said bushings.

In the exemplary form hereinillustrated the invention comprises a casing in the form of a cylindrical tube 10 of fibre or other suitable insulating material having two metallic bushings or heads 11 and 12 rigidly attached to the opposite ends thereof in any suitable way. The heads have at their outer ends a plurality of abutments or webs 13, (F ig.- 5) in this instance four, extending radially inward and forming alined non-circular apertures 14. In the present instance these apertures are substantially rectangular and iden' tical in size; Two of the webs of each head are provided with opposed notches 15 offset from-the central portion of the webs.

The outer end of each of the heads 11 and 12 is provided with a peripheral groove 16 forming an annular flange 17 and a shoulder 18.

In the present embodiment we provide means permanently carried by the casing, which means are adapted detachably to engage end closures or caps to secure them rigidly to the casing. Preferably this means comprises a tubular collar 19 on each end of the casing.

The collars 19 are adapted to slide on the heads 11 and 12 and have suitable means such as the inwardly extending annular flanges 2Q at the inner ends thereof which. project into 9 the-grooves 16 to hold the collars against displacement from the head, yet permit free rotation thereon. Preferably the outer surface of each collar 19 is knurled to permit of convenient manipulation. 10

the unit together in operable relation. The terminal blade unit in the preferred form herein shown comprises generally a pair of terminal knife blades 27 and 28, one of which carries an end inclosure permanently mount- 7 ed thereon. A fusible element 30 connects said blades; and an insulating bridge section comprising a pair of metallic clips 31 permanently secured to the blades and joined by an insulating bar 32, secures the blades rigidly together in spaced relation. The terminal blade unit thus formed provides a rigid structure which may be readily inserted or removed from the casing for inspection or renewal of the fusible link orthe bridge.

a The blades are suitably formed contact members having inner portionsthereof, nar-. rower than the outer portions, thus forming shoulders 33 adapted to abut against theouter faces of the webs 13. An abutment flange or. ledge 29 is provided on the blade 28 and in this instance comprises a small oblong plate, having rounded ends and provided with a central slot, which may be slipped over the narrower portion of the blade. The ledge lies closely along the shoulder 33 on the blade 28 and is secured rigidly thereto in any suita ble manner, as by soldering- In size the ledge is preferably shorterin length than the width of the wider portion of the blade to leave a portion of the shoulder on each side of the blade exposed but the ledge is wider than thethickness of the blade for a purpose later to beexplained.

End closures or caps 21 and 22 are pro vided, one for each end of the casing 10 and preferably are in the form of plates or disks of substantial thickness having diametrical slots or apertures 23 therein through which the. terminal blades extend. The caps21 and 22 are'externally screw-threaded to engage corresponding threads provided in the tubular collars 19, held on the heads. A plurality of pro ect1ng pinsor bosses 24 are formed on one face of each cap and are adapted to engage in the pockets or recesses 25 provided by the angular intersection of the webs 13 on each head. This cooperative relation between the caps 21 and 22 and the terminal blades on one hand andthe heads 11 and 12 and the casing 10 on the other prevents relative rotation therebetween and assures that the terminal blade unit will be properly disposed with tion to the end cap 21 on the blade 27, a second head to protect said head from molten metal ledge 34: similar to the ledge 29 may if desired 7 be provided to aid in properly positloning the cap 21 relative to the blade. I 3

Each of the clips 31 (Fig. 7) which effect a bond between the blades 27 and 28 and the insulating bar 32 comprises a flat bodysection or plate 35 which has at one end suitable means for securely engaging the blade and at the end .of the clip 31 and has the ends thereof bent inwardly toward each other and substantially parallel with the plate 35 and in snug engagement with the blade; The second pair of flanges 37 are arranged to extend across the depth of the blade. I Preferably the clip is permanently secured to the blade, as by soldering the clip thereto, in which man ner a perfectly rigid union between each blade and clip is attained. V 1

The free end of the cliphas both sides bent outwardly at right angles to the plate 35 to provide a third pair of flanges 38 extending in the opposite direction from that in which the blade engaging flanges 36, 37- extend. These flanges 38 form a channel or trough arranged to receive the insulating bar32 which is secured therein by means of a screw 39 extending through a suitable aperture in the bar vinto engagement with a screw threaded opening 40 in the clip.

The fusible element is secured to the blades in-the present instance by bolts 41 passing 7 stance such a washer is shown with outwardly extending flanges surrounding the bolt when the fusible element is blown.

It will be apparent that a structure has been provided by which a termmal unit hav 7 ing inherent rigid ty is produced. The vclips.

permanently secured as they are to the terminal blades and detachably receiving the insulating bar for replacement, are a means for joining the knife blades to the insulating bar which prevent relative rotational,longitudinal or transverse movement therebetween,

while the channels or troughs which receive the bar prevent pivotal movement between the bar andthe blade. 1

When it is necessary to renew a blown fuse element the collars 19 are rotated to release the end caps 21 and 22. One of the end caps 22 is then free to he slipped from its blade 28 and, upon movement of that blade transversely of the axis of the fuse to disengage the shoulders 33 of the blade from the webs 13 and register the blade with the opposed notches 15, the terminal blade unit may be withdrawn longitudinally through the casing 10.

After the terminal unit has been removed from the casing the bolts 41 may be slightly loosened, the unmelted ends of the blown link removed and a new clamped by the bolts. The fusible links may, as is customary, be provided with open end slots so that complete removal of the bolts 41. is unnecessary.

The replacement of the link being completed, the unit may be re-inserted into the casing from either end. In doing so the blade 28 is inserted first through the notches 15 in the webs 18 of one head and then the other, and the end cap 21, which is rigid with the terminal unit, is positioned. so that the bosses 24 thereon engage the recesses 25 in the head 11 when the unit is fully inserted in the casing. The opposed blade 28 is then in posi tion to be moved transversely of the axis of the fuse to engage the shoulders 33 with the webs 13. The free end cap 22 is then slipped over the blade 28 to engage the bosses 24 thereon with the recesses 25 in the webs in the same manner as at the opposite end. Thus the blades are alined before the assembly is completed and after the collars 19 of each head have been screwed tightly onto the end caps and the end caps thereby clamped against the ends of the casing, the blades are held against movement rotationally, transversely or longitudinally relative to the easing. V 7

As shown clearly in Fig. 2 the ledge 29 is arranged to abut the end cap whenthe fuse is assembled to prevent the escape of gases, generated by blowing of a fuse,directly into the atmosphere through the slot 23. Such venting as is desirable occurs through the tortuous passages, formed between the parts due to their relative positions or loosely fitting interengagement.

By mounting the securing means permanently on the casing for mechanical engagement with the closures, it has been assured that the closures will invariably be drawn. into a close, immovable abutment againstthe end of the'casing, thus providing maximum strength for the assembled fuse. The terminal bladeunit, in itself, is constructed in such a manner as to provide the great ri gidity, especially desirable since the unit is constantly being inserted and withdrawn from the casing. Moreover,tl1e number of separable parts, which constitute the fuse,

link inserted to be have been reduced by incorporating them in 7 either the casing or the terminal blade unit whereby the renewal of the fusible link has been simplified.

It will be apparent therefore that an improved cartridge fuse ofsirnple construction has been provided embodying a terminal blade structure which presents a perfectly rigid structure when assembled through the use of novel means for securing the parts together. i

We claim as our invention:

1. A renewable cartridge fuse having, in combination, a casing, a terminal blade, 2. plate forming an end closure slidable on said blade, and a collar carried by said casing, said collar being internally screw threaded to engage corresponding threads exteriorly I formed on said plate to secure said plate and blade on said casing.

2; A renewable cartridge fuse having, in combination, a casing, a terminal blade extending from one end thereof, and means to secure said terminal blade to said casing, said means comprising an apertured plate slidable on said blade, a rotatable collar permanently carried on said casing adapted detachably to engage said plate, and means on said plate engaging said casing to prevent relative rotation therebetween.

3. A renewable cartridge fuse having, in combination, a casing, a terminal blade extending from one end thereof, a disk rigidly mounted on said blade for closing the end of said casing, and means permanently and rotatably carried by said casing arranged to engage said disk to draw said disk inwardly of said easing into rigid abutment against the end of said casing.

4. A renewable cartridge fuse having, in combination, a casing, a metallic head secured upon one end of said casing, an internally screw threaded collar permanently carried by said head for free rotational and limited longitudinal movement relative thereto, an end closure having an aperture therethrough adapted to abut the end of said head, engaging means between said head and clo sure preventing relative rotational movement therebetween, said closure being externally screw threaded to be engaged by said collar to hold said closure on said casing, and a terminal blade extending through said aperture in said closure.

5. A renewable cartridge fuse having, in combination, a casing, a terminal blade, and means to secure said terminal blade to one end of said casing, said means comprising a head having a peripheral groove, secured upon the end of saidcasing, an internally screw threaded collar having an inwardly projecting peripheral flange engaging said groove, and a disk slidable on said blade having head engaging means to prevent rotation of said blade relative to said casing and to center lllll' saidblade therein, saiddisk being externally screw threaded to be detachably engaged plates to clamp said plates snugly against said casing p I 7. A renewable cartridge fuse having, in

combination, a casing,a metallic head on each 1 adapted detachablyto secure said. closure end of said casing, a-terminal blade unit extending therethroughcomprising a palr or terminal blades, and means to secure said unit rigidly to the'casing comprising end closures on said bladesbeyondwhich the blades project, said closures havinghead engaging meansto prevent rotation and lateral displacement of said blades relative to said casing, and rotatable collars nondetachably' carried by said heads and adapted detachably to engage the closures to draw said closures into engagement with the heads.

8. A renewable cartridge fuse having, in

combination, a casing, a terminal blade unit including a pair of terminal blades, a fusible element detachably secured therebetween and an end closure rigidly secured to one of said blades, means permanently mounted on said casing adapted detachably to secure said end closure in rigid abutment against the end of said casing, and means for securing the other blade to the casing. H

9- A renewable cartridge fuse having, in

combination, a pair of terminal blades, a

fusible link connecting said blades,a casing for supporting said blades and said link therein, means carried by each blade for positioning that blade relative to said casing, and means carried permanently androtatably on said casing arrangedfor threaded engagement with said means carried on the blades to se'cure'the blades insaid position on the casing.

10. A renewable cartridge fuse having, in combination, a casing, a pair of *ternnnalblades, a fusible element detachably" secured therebetween, a closureffor one end of said casing rigidly secured to one of said blades, means permanently mounted on said casing thereon, an apertured closureslidable over the other of said blades, and means on said casing todetachably secure the last mentionrd closure on said casing.

11. A renewable cartridge fuse having, in combination} a casing, a pair of terminal blades, a fusible element detachably secured theiebetween, closure. for one end of said 'cartri lge a pair of terminal blades, a fusible elementcasing rigidly mounted on one of said blades, 7 a second closure centrally apertured to slide, over theother of said blades, means on'each of said closures eu -aging said casing to aline said blades and to prevent rotational and lateral displacem ent. thereof in said casing, and a rotatable collar carriedpermanently on each end of said-casing adapted detachably to engage the corresponding closure to secure the parts in assembled relation.

1.2. A. terminal blade'unit for renewable fuses comprising, in combination,

tberebetween, and a bridge section joining said blades and comprising a clip permanently secured to the inner portion of each blade, a pair of flanges rising perpendicularly from tbeedges of the free end of each clip to form a channel, an insulating member adapted to be, received in said channel in each clip, and detachable means securing said insulating member therein. I V

13. A terminal blade unit for renewable cartridge fuses comprising, in combination, two blades, a fusible element joining said blades, and a bridge section securing said blades in spaced relation, said bridge section comprising two metallic end clips joined by an insulating member, each of said clips com- 7 prising a portion lying along one side of the blade and one side of the insulating member, a pair of flanges rising from opposite sides of said portion adapted to embracesai'd blade, a second pair offlanges rising in the same direction and spaced from the first mentioned pair of flanges adapted toengage the side edges of said'blade, athird pair of flanges extending in the opposite direction from the other two pairs of flanges to form a trough to receive-said insulating member, and means to secure said member detachably tosaid clips. i

14. A terminal blade unit for renewable cartridge fuses comprising,in combination, two blades, a fusible element therebetween,

fit)

means detachably securing-said fusible ele-' ment to each of said blades, and a bridge section joining said blades and comprising clips permanently secured to each of said blades, the free ends of said clips having channellike portions, an insulating member having ends adapted to be received in said channel portions and detachable means for securing said member to-the clips.

v 15. A refillable cartridge fuse having, in

combination, a hollow insulating body havlng a rotatable collar permanently mounted on each end, a' pair of fuse terminals connected by a, fusible strip, a disk rigid with one of said terminals for closingone end of said body, havmg means thereon for center:

ing said terminal on said body and for pre r venting relative rotation therebetween, a disk slldable over the other vof said terminals for closing the other end of said body and hav- 5 ing means thereon for centering that terminal on the body and preventin relative rotation therebetween, said rotata le collars on each end of the body having a threaded engagement with the respective disks to retain said disks against longitudinal and transverse movement.

16. A renewable cartridge fuse com rising, in combination, a hollow insulated ody portion, metallic heads thereon having a plurality of inwardly and laterally projecting webs defining similar irregular apertures, a pair of terminal blades connected by a fusible link and having shoulders thereon arranged to abut said webs, a plate rigidly mounted on one of said blades, said plate having bosses thereon arranged to engage the webs of one of said heads to prevent relative rotation between the body and the blade, a similar plate slidable on the other of said blades, and a collar permanently mounted on each head having a rotative interengagement with the corresponding plate to secure said blades in position in the said body portion.

In testimony whereof we have hereunto afiixed our signatures.

CLARENCE T. MoDONALD. HERBERT RAY COOK. 

